Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * main.c
4 : * Stub main() routine for the postgres executable.
5 : *
6 : * This does some essential startup tasks for any incarnation of postgres
7 : * (postmaster, standalone backend, standalone bootstrap process, or a
8 : * separately exec'd child of a postmaster) and then dispatches to the
9 : * proper FooMain() routine for the incarnation.
10 : *
11 : *
12 : * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
13 : * Portions Copyright (c) 1994, Regents of the University of California
14 : *
15 : *
16 : * IDENTIFICATION
17 : * src/backend/main/main.c
18 : *
19 : *-------------------------------------------------------------------------
20 : */
21 : #include "postgres.h"
22 :
23 : #include <unistd.h>
24 :
25 : #if defined(WIN32)
26 : #include <crtdbg.h>
27 : #endif
28 :
29 : #if defined(__NetBSD__)
30 : #include <sys/param.h>
31 : #endif
32 :
33 : #include "bootstrap/bootstrap.h"
34 : #include "common/username.h"
35 : #include "miscadmin.h"
36 : #include "postmaster/postmaster.h"
37 : #include "tcop/tcopprot.h"
38 : #include "utils/help_config.h"
39 : #include "utils/memutils.h"
40 : #include "utils/pg_locale.h"
41 : #include "utils/ps_status.h"
42 :
43 :
44 : const char *progname;
45 : static bool reached_main = false;
46 :
47 : /* names of special must-be-first options for dispatching to subprograms */
48 : static const char *const DispatchOptionNames[] =
49 : {
50 : [DISPATCH_CHECK] = "check",
51 : [DISPATCH_BOOT] = "boot",
52 : [DISPATCH_FORKCHILD] = "forkchild",
53 : [DISPATCH_DESCRIBE_CONFIG] = "describe-config",
54 : [DISPATCH_SINGLE] = "single",
55 : /* DISPATCH_POSTMASTER has no name */
56 : };
57 :
58 : StaticAssertDecl(lengthof(DispatchOptionNames) == DISPATCH_POSTMASTER,
59 : "array length mismatch");
60 :
61 : static void startup_hacks(const char *progname);
62 : static void init_locale(const char *categoryname, int category, const char *locale);
63 : static void help(const char *progname);
64 : static void check_root(const char *progname);
65 :
66 :
67 : /*
68 : * Any Postgres server process begins execution here.
69 : */
70 : int
71 3774 : main(int argc, char *argv[])
72 : {
73 3774 : bool do_check_root = true;
74 3774 : DispatchOption dispatch_option = DISPATCH_POSTMASTER;
75 :
76 3774 : reached_main = true;
77 :
78 : /*
79 : * If supported on the current platform, set up a handler to be called if
80 : * the backend/postmaster crashes with a fatal signal or exception.
81 : */
82 : #if defined(WIN32)
83 : pgwin32_install_crashdump_handler();
84 : #endif
85 :
86 3774 : progname = get_progname(argv[0]);
87 :
88 : /*
89 : * Platform-specific startup hacks
90 : */
91 3774 : startup_hacks(progname);
92 :
93 : /*
94 : * Remember the physical location of the initially given argv[] array for
95 : * possible use by ps display. On some platforms, the argv[] storage must
96 : * be overwritten in order to set the process title for ps. In such cases
97 : * save_ps_display_args makes and returns a new copy of the argv[] array.
98 : *
99 : * save_ps_display_args may also move the environment strings to make
100 : * extra room. Therefore this should be done as early as possible during
101 : * startup, to avoid entanglements with code that might save a getenv()
102 : * result pointer.
103 : */
104 3774 : argv = save_ps_display_args(argc, argv);
105 :
106 : /*
107 : * Fire up essential subsystems: error and memory management
108 : *
109 : * Code after this point is allowed to use elog/ereport, though
110 : * localization of messages may not work right away, and messages won't go
111 : * anywhere but stderr until GUC settings get loaded.
112 : */
113 3774 : MyProcPid = getpid();
114 3774 : MemoryContextInit();
115 :
116 : /*
117 : * Set reference point for stack-depth checking. (There's no point in
118 : * enabling this before error reporting works.)
119 : */
120 3774 : (void) set_stack_base();
121 :
122 : /*
123 : * Set up locale information
124 : */
125 3774 : set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("postgres"));
126 :
127 : /*
128 : * Collation is handled by pg_locale.c, and the behavior is dependent on
129 : * the provider. strcoll(), etc., should not be called directly.
130 : */
131 3774 : init_locale("LC_COLLATE", LC_COLLATE, "C");
132 :
133 : /*
134 : * In the postmaster, absorb the environment value for LC_CTYPE.
135 : * Individual backends will change it later to pg_database.datctype, but
136 : * the postmaster cannot do that. If we leave it set to "C" then message
137 : * localization might not work well in the postmaster.
138 : */
139 3774 : init_locale("LC_CTYPE", LC_CTYPE, "");
140 :
141 : /*
142 : * LC_MESSAGES will get set later during GUC option processing, but we set
143 : * it here to allow startup error messages to be localized.
144 : */
145 : #ifdef LC_MESSAGES
146 3774 : init_locale("LC_MESSAGES", LC_MESSAGES, "");
147 : #endif
148 :
149 : /* We keep these set to "C" always. See pg_locale.c for explanation. */
150 3774 : init_locale("LC_MONETARY", LC_MONETARY, "C");
151 3774 : init_locale("LC_NUMERIC", LC_NUMERIC, "C");
152 3774 : init_locale("LC_TIME", LC_TIME, "C");
153 :
154 : /*
155 : * Now that we have absorbed as much as we wish to from the locale
156 : * environment, remove any LC_ALL setting, so that the environment
157 : * variables installed by pg_perm_setlocale have force.
158 : */
159 3774 : unsetenv("LC_ALL");
160 :
161 : /*
162 : * Catch standard options before doing much else, in particular before we
163 : * insist on not being root.
164 : */
165 3774 : if (argc > 1)
166 : {
167 3774 : if (strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") == 0)
168 : {
169 2 : help(progname);
170 2 : exit(0);
171 : }
172 3772 : if (strcmp(argv[1], "--version") == 0 || strcmp(argv[1], "-V") == 0)
173 : {
174 1544 : fputs(PG_BACKEND_VERSIONSTR, stdout);
175 1544 : exit(0);
176 : }
177 :
178 : /*
179 : * In addition to the above, we allow "--describe-config" and "-C var"
180 : * to be called by root. This is reasonably safe since these are
181 : * read-only activities. The -C case is important because pg_ctl may
182 : * try to invoke it while still holding administrator privileges on
183 : * Windows. Note that while -C can normally be in any argv position,
184 : * if you want to bypass the root check you must put it first. This
185 : * reduces the risk that we might misinterpret some other mode's -C
186 : * switch as being the postmaster/postgres one.
187 : */
188 2228 : if (strcmp(argv[1], "--describe-config") == 0)
189 0 : do_check_root = false;
190 2228 : else if (argc > 2 && strcmp(argv[1], "-C") == 0)
191 2 : do_check_root = false;
192 : }
193 :
194 : /*
195 : * Make sure we are not running as root, unless it's safe for the selected
196 : * option.
197 : */
198 2228 : if (do_check_root)
199 2226 : check_root(progname);
200 :
201 : /*
202 : * Dispatch to one of various subprograms depending on first argument.
203 : */
204 :
205 2228 : if (argc > 1 && argv[1][0] == '-' && argv[1][1] == '-')
206 482 : dispatch_option = parse_dispatch_option(&argv[1][2]);
207 :
208 2228 : switch (dispatch_option)
209 : {
210 252 : case DISPATCH_CHECK:
211 252 : BootstrapModeMain(argc, argv, true);
212 : break;
213 104 : case DISPATCH_BOOT:
214 104 : BootstrapModeMain(argc, argv, false);
215 : break;
216 0 : case DISPATCH_FORKCHILD:
217 : #ifdef EXEC_BACKEND
218 : SubPostmasterMain(argc, argv);
219 : #else
220 : Assert(false); /* should never happen */
221 : #endif
222 0 : break;
223 0 : case DISPATCH_DESCRIBE_CONFIG:
224 0 : GucInfoMain();
225 : break;
226 124 : case DISPATCH_SINGLE:
227 124 : PostgresSingleUserMain(argc, argv,
228 124 : strdup(get_user_name_or_exit(progname)));
229 : break;
230 1748 : case DISPATCH_POSTMASTER:
231 1748 : PostmasterMain(argc, argv);
232 : break;
233 : }
234 :
235 : /* the functions above should not return */
236 0 : abort();
237 : }
238 :
239 : /*
240 : * Returns the matching DispatchOption value for the given option name. If no
241 : * match is found, DISPATCH_POSTMASTER is returned.
242 : */
243 : DispatchOption
244 2020 : parse_dispatch_option(const char *name)
245 : {
246 10320 : for (int i = 0; i < lengthof(DispatchOptionNames); i++)
247 : {
248 : /*
249 : * Unlike the other dispatch options, "forkchild" takes an argument,
250 : * so we just look for the prefix for that one. For non-EXEC_BACKEND
251 : * builds, we never want to return DISPATCH_FORKCHILD, so skip over it
252 : * in that case.
253 : */
254 8780 : if (i == DISPATCH_FORKCHILD)
255 : {
256 : #ifdef EXEC_BACKEND
257 : if (strncmp(DispatchOptionNames[DISPATCH_FORKCHILD], name,
258 : strlen(DispatchOptionNames[DISPATCH_FORKCHILD])) == 0)
259 : return DISPATCH_FORKCHILD;
260 : #endif
261 1664 : continue;
262 : }
263 :
264 7116 : if (strcmp(DispatchOptionNames[i], name) == 0)
265 480 : return (DispatchOption) i;
266 : }
267 :
268 : /* no match means this is a postmaster */
269 1540 : return DISPATCH_POSTMASTER;
270 : }
271 :
272 : /*
273 : * Place platform-specific startup hacks here. This is the right
274 : * place to put code that must be executed early in the launch of any new
275 : * server process. Note that this code will NOT be executed when a backend
276 : * or sub-bootstrap process is forked, unless we are in a fork/exec
277 : * environment (ie EXEC_BACKEND is defined).
278 : *
279 : * XXX The need for code here is proof that the platform in question
280 : * is too brain-dead to provide a standard C execution environment
281 : * without help. Avoid adding more here, if you can.
282 : */
283 : static void
284 3774 : startup_hacks(const char *progname)
285 : {
286 : /*
287 : * Windows-specific execution environment hacking.
288 : */
289 : #ifdef WIN32
290 : {
291 : WSADATA wsaData;
292 : int err;
293 :
294 : /* Make output streams unbuffered by default */
295 : setvbuf(stdout, NULL, _IONBF, 0);
296 : setvbuf(stderr, NULL, _IONBF, 0);
297 :
298 : /* Prepare Winsock */
299 : err = WSAStartup(MAKEWORD(2, 2), &wsaData);
300 : if (err != 0)
301 : {
302 : write_stderr("%s: WSAStartup failed: %d\n",
303 : progname, err);
304 : exit(1);
305 : }
306 :
307 : /*
308 : * By default abort() only generates a crash-dump in *non* debug
309 : * builds. As our Assert() / ExceptionalCondition() uses abort(),
310 : * leaving the default in place would make debugging harder.
311 : *
312 : * MINGW's own C runtime doesn't have _set_abort_behavior(). When
313 : * targeting Microsoft's UCRT with mingw, it never links to the debug
314 : * version of the library and thus doesn't need the call to
315 : * _set_abort_behavior() either.
316 : */
317 : #if !defined(__MINGW32__) && !defined(__MINGW64__)
318 : _set_abort_behavior(_CALL_REPORTFAULT | _WRITE_ABORT_MSG,
319 : _CALL_REPORTFAULT | _WRITE_ABORT_MSG);
320 : #endif /* !defined(__MINGW32__) &&
321 : * !defined(__MINGW64__) */
322 :
323 : /*
324 : * SEM_FAILCRITICALERRORS causes more errors to be reported to
325 : * callers.
326 : *
327 : * We used to also specify SEM_NOGPFAULTERRORBOX, but that prevents
328 : * windows crash reporting from working. Which includes registered
329 : * just-in-time debuggers, making it unnecessarily hard to debug
330 : * problems on windows. Now we try to disable sources of popups
331 : * separately below (note that SEM_NOGPFAULTERRORBOX did not actually
332 : * prevent all sources of such popups).
333 : */
334 : SetErrorMode(SEM_FAILCRITICALERRORS);
335 :
336 : /*
337 : * Show errors on stderr instead of popup box (note this doesn't
338 : * affect errors originating in the C runtime, see below).
339 : */
340 : _set_error_mode(_OUT_TO_STDERR);
341 :
342 : /*
343 : * In DEBUG builds, errors, including assertions, C runtime errors are
344 : * reported via _CrtDbgReport. By default such errors are displayed
345 : * with a popup (even with NOGPFAULTERRORBOX), preventing forward
346 : * progress. Instead report such errors stderr (and the debugger).
347 : * This is C runtime specific and thus the above incantations aren't
348 : * sufficient to suppress these popups.
349 : */
350 : _CrtSetReportMode(_CRT_ERROR, _CRTDBG_MODE_FILE | _CRTDBG_MODE_DEBUG);
351 : _CrtSetReportFile(_CRT_ERROR, _CRTDBG_FILE_STDERR);
352 : _CrtSetReportMode(_CRT_ASSERT, _CRTDBG_MODE_FILE | _CRTDBG_MODE_DEBUG);
353 : _CrtSetReportFile(_CRT_ASSERT, _CRTDBG_FILE_STDERR);
354 : _CrtSetReportMode(_CRT_WARN, _CRTDBG_MODE_FILE | _CRTDBG_MODE_DEBUG);
355 : _CrtSetReportFile(_CRT_WARN, _CRTDBG_FILE_STDERR);
356 : }
357 : #endif /* WIN32 */
358 3774 : }
359 :
360 :
361 : /*
362 : * Make the initial permanent setting for a locale category. If that fails,
363 : * perhaps due to LC_foo=invalid in the environment, use locale C. If even
364 : * that fails, perhaps due to out-of-memory, the entire startup fails with it.
365 : * When this returns, we are guaranteed to have a setting for the given
366 : * category's environment variable.
367 : */
368 : static void
369 22644 : init_locale(const char *categoryname, int category, const char *locale)
370 : {
371 22644 : if (pg_perm_setlocale(category, locale) == NULL &&
372 0 : pg_perm_setlocale(category, "C") == NULL)
373 0 : elog(FATAL, "could not adopt \"%s\" locale nor C locale for %s",
374 : locale, categoryname);
375 22644 : }
376 :
377 :
378 :
379 : /*
380 : * Help display should match the options accepted by PostmasterMain()
381 : * and PostgresMain().
382 : *
383 : * XXX On Windows, non-ASCII localizations of these messages only display
384 : * correctly if the console output code page covers the necessary characters.
385 : * Messages emitted in write_console() do not exhibit this problem.
386 : */
387 : static void
388 2 : help(const char *progname)
389 : {
390 2 : printf(_("%s is the PostgreSQL server.\n\n"), progname);
391 2 : printf(_("Usage:\n %s [OPTION]...\n\n"), progname);
392 2 : printf(_("Options:\n"));
393 2 : printf(_(" -B NBUFFERS number of shared buffers\n"));
394 2 : printf(_(" -c NAME=VALUE set run-time parameter\n"));
395 2 : printf(_(" -C NAME print value of run-time parameter, then exit\n"));
396 2 : printf(_(" -d 1-5 debugging level\n"));
397 2 : printf(_(" -D DATADIR database directory\n"));
398 2 : printf(_(" -e use European date input format (DMY)\n"));
399 2 : printf(_(" -F turn fsync off\n"));
400 2 : printf(_(" -h HOSTNAME host name or IP address to listen on\n"));
401 2 : printf(_(" -i enable TCP/IP connections (deprecated)\n"));
402 2 : printf(_(" -k DIRECTORY Unix-domain socket location\n"));
403 : #ifdef USE_SSL
404 2 : printf(_(" -l enable SSL connections\n"));
405 : #endif
406 2 : printf(_(" -N MAX-CONNECT maximum number of allowed connections\n"));
407 2 : printf(_(" -p PORT port number to listen on\n"));
408 2 : printf(_(" -s show statistics after each query\n"));
409 2 : printf(_(" -S WORK-MEM set amount of memory for sorts (in kB)\n"));
410 2 : printf(_(" -V, --version output version information, then exit\n"));
411 2 : printf(_(" --NAME=VALUE set run-time parameter\n"));
412 2 : printf(_(" --describe-config describe configuration parameters, then exit\n"));
413 2 : printf(_(" -?, --help show this help, then exit\n"));
414 :
415 2 : printf(_("\nDeveloper options:\n"));
416 2 : printf(_(" -f s|i|o|b|t|n|m|h forbid use of some plan types\n"));
417 2 : printf(_(" -O allow system table structure changes\n"));
418 2 : printf(_(" -P disable system indexes\n"));
419 2 : printf(_(" -t pa|pl|ex show timings after each query\n"));
420 2 : printf(_(" -T send SIGABRT to all backend processes if one dies\n"));
421 2 : printf(_(" -W NUM wait NUM seconds to allow attach from a debugger\n"));
422 :
423 2 : printf(_("\nOptions for single-user mode:\n"));
424 2 : printf(_(" --single selects single-user mode (must be first argument)\n"));
425 2 : printf(_(" DBNAME database name (defaults to user name)\n"));
426 2 : printf(_(" -d 0-5 override debugging level\n"));
427 2 : printf(_(" -E echo statement before execution\n"));
428 2 : printf(_(" -j do not use newline as interactive query delimiter\n"));
429 2 : printf(_(" -r FILENAME send stdout and stderr to given file\n"));
430 :
431 2 : printf(_("\nOptions for bootstrapping mode:\n"));
432 2 : printf(_(" --boot selects bootstrapping mode (must be first argument)\n"));
433 2 : printf(_(" --check selects check mode (must be first argument)\n"));
434 2 : printf(_(" DBNAME database name (mandatory argument in bootstrapping mode)\n"));
435 2 : printf(_(" -r FILENAME send stdout and stderr to given file\n"));
436 :
437 2 : printf(_("\nPlease read the documentation for the complete list of run-time\n"
438 : "configuration settings and how to set them on the command line or in\n"
439 : "the configuration file.\n\n"
440 : "Report bugs to <%s>.\n"), PACKAGE_BUGREPORT);
441 2 : printf(_("%s home page: <%s>\n"), PACKAGE_NAME, PACKAGE_URL);
442 2 : }
443 :
444 :
445 :
446 : static void
447 2226 : check_root(const char *progname)
448 : {
449 : #ifndef WIN32
450 2226 : if (geteuid() == 0)
451 : {
452 0 : write_stderr("\"root\" execution of the PostgreSQL server is not permitted.\n"
453 : "The server must be started under an unprivileged user ID to prevent\n"
454 : "possible system security compromise. See the documentation for\n"
455 : "more information on how to properly start the server.\n");
456 0 : exit(1);
457 : }
458 :
459 : /*
460 : * Also make sure that real and effective uids are the same. Executing as
461 : * a setuid program from a root shell is a security hole, since on many
462 : * platforms a nefarious subroutine could setuid back to root if real uid
463 : * is root. (Since nobody actually uses postgres as a setuid program,
464 : * trying to actively fix this situation seems more trouble than it's
465 : * worth; we'll just expend the effort to check for it.)
466 : */
467 2226 : if (getuid() != geteuid())
468 : {
469 0 : write_stderr("%s: real and effective user IDs must match\n",
470 : progname);
471 0 : exit(1);
472 : }
473 : #else /* WIN32 */
474 : if (pgwin32_is_admin())
475 : {
476 : write_stderr("Execution of PostgreSQL by a user with administrative permissions is not\n"
477 : "permitted.\n"
478 : "The server must be started under an unprivileged user ID to prevent\n"
479 : "possible system security compromises. See the documentation for\n"
480 : "more information on how to properly start the server.\n");
481 : exit(1);
482 : }
483 : #endif /* WIN32 */
484 2226 : }
485 :
486 : /*
487 : * At least on linux, set_ps_display() breaks /proc/$pid/environ. The
488 : * sanitizer library uses /proc/$pid/environ to implement getenv() as it wants
489 : * to work independent of libc. When just using undefined and alignment
490 : * sanitizers, the sanitizer library is only initialized when the first error
491 : * occurs, by which time we've often already called set_ps_display(),
492 : * preventing the sanitizer libraries from seeing the options.
493 : *
494 : * We can work around that by defining __ubsan_default_options, a weak symbol
495 : * libsanitizer uses to get defaults from the application, and return
496 : * getenv("UBSAN_OPTIONS"). But only if main already was reached, so that we
497 : * don't end up relying on a not-yet-working getenv().
498 : *
499 : * As this function won't get called when not running a sanitizer, it doesn't
500 : * seem necessary to only compile it conditionally.
501 : */
502 : const char *__ubsan_default_options(void);
503 : const char *
504 0 : __ubsan_default_options(void)
505 : {
506 : /* don't call libc before it's guaranteed to be initialized */
507 0 : if (!reached_main)
508 0 : return "";
509 :
510 0 : return getenv("UBSAN_OPTIONS");
511 : }
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